Re: Time delayed LR (WAS Re: logical replication restrictions)

At Thu, 15 Dec 2022 09:23:12 +0530, Amit Kapila <amit.kapila16@gmail.com> wrote in 
> On Thu, Dec 15, 2022 at 7:16 AM Kyotaro Horiguchi
> <horikyota.ntt@gmail.com> wrote:
> > Allowing walsender to finish ignoring replication status
> > wouldn't be great.
> >
> 
> Yes, that would be ideal. But do you know why that is a must?

I believe a graceful shutdown (fast and smart) of a replication set is expected to be in sync.  Of course we can change
thepolicy to allow walsnder to stop before confirming all WAL have been applied. However walsender doesn't have an idea
of wheter the peer is intentionally delaying or not.
 

> >  One idea is to let logical workers send delaying
> > status.
> >
> 
> How can that help?

If logical worker notifies "I'm intentionally pausing replication for
now, so if you wan to shutting down, plese go ahead ignoring me",
publisher can legally run a (kind of) dirty shut down.

# It looks a bit too much, though..

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center